What about ghrelin and leptin?

You may have heard sleep explained through two hormones:

Ghrelin — often called a “hunger hormone”

and

Leptin — involved in signalling longer-term energy availability and satiety.

Early sleep research suggested that sleep restriction could increase ghrelin and reduce leptin.

That made for an appealing explanation:

less sleep → more ghrelin + less leptin → more hunger

But human physiology is not quite that simple.

A more recent systematic review looking specifically at sex differences found inconsistent responses in leptin, ghrelin, insulin and other appetite-related hormones following sleep restriction.

Likewise, a systematic review of clinical trials found that sleep restriction increased appetite and energy intake overall, while changes in circulating ghrelin, leptin and cortisol were not consistent across studies.

So I would not tell someone:

“Your cravings are caused by high ghrelin.”

A better explanation is:

Sleep loss can change appetite regulation through several hormonal, neurological and behavioural pathways at once.

Appetite is not just a hormone problem

This is important.

Imagine you have slept badly.

The following day you may:

• feel more tired
• move less
• have less patience
• want a quick energy lift
• find planning meals harder
• rely more on convenience foods
• reach for caffeine
• feel less motivated to exercise
• find highly palatable foods more appealing

That is not a failure of willpower.

It is a predictable interaction between physiology, environment and behaviour.

This is why I prefer to look at what poor sleep leads to, rather than blaming one hormone.

Sleep and food reward

Poor sleep may also affect how appealing food feels.

When we are tired, the brain may respond differently to highly rewarding foods.

Foods that combine:

• sugar
• fat
• salt

can become particularly attractive when energy and concentration are low.

This can make an evening of poor sleep show up the next day as:

“I just cannot stop thinking about food.”

That does not necessarily mean genuine energy deficiency.

It may reflect a combination of:

• altered reward processing
• fatigue
• appetite signalling
• habit
• opportunity
• emotional regulation

Again, the bigger picture matters.

Sleep and blood glucose

Sleep is also relevant to glucose regulation.

Sleep restriction has been linked with poorer insulin sensitivity and disturbances in carbohydrate metabolism in experimental studies, and reviews continue to describe sleep disruption as relevant to metabolic health.

That means the same meal may not necessarily produce the same metabolic response after a period of poor sleep as it does when you are well rested.

For someone already concerned about:

• insulin resistance
• HbA1c
• fasting glucose
• body composition
• metabolic health

sleep deserves attention alongside food and exercise.

[Explore: What is insulin resistance? →]

[Explore: Understanding blood glucose and HbA1c →]

Sleep, appetite and perimenopause

This is where several parts of midlife physiology can intersect.

Consider the following pattern:

Hormonal transition

may contribute to:

hot flushes / night sweats

which may contribute to:

fragmented sleep

which can contribute to:

fatigue + increased appetite + different food choices + less movement

which may make it harder to support:

body composition and metabolic health

That does not mean menopause automatically causes weight gain.

It shows why looking only at calories can miss part of the story.

If poor sleep is driving the rest of the pattern, simply making the diet more restrictive may make life harder without addressing the factor that is making dietary change difficult.

Sleep and cortisol

Cortisol is another hormone that is often blamed for midlife weight gain.

Cortisol is essential.

It helps regulate:

• waking and alertness
• blood pressure
• glucose availability
• responses to stress

It normally follows a daily rhythm.

Sleep deprivation and circadian disruption can affect cortisol patterns, but it is misleading to say:

“High cortisol causes belly fat.”

Body composition is influenced by many factors.

For someone experiencing prolonged stress and poor sleep, I am more interested in questions such as:

• are you sleeping enough?
• are you waking frequently?
• are you relying heavily on caffeine?
• is stress changing how you eat?
• are you moving less?
• are you drinking more alcohol?
• are menopausal symptoms interrupting sleep?

These give us something meaningful to work with.

Night sweats can create a metabolic knock-on effect

Night sweats are more than an inconvenience.

If they repeatedly interrupt sleep, the effects can carry into the following day.

You may feel:

• more hungry
• less energetic
• more irritable
• less inclined to exercise
• more dependent on caffeine
• less interested in preparing meals

This is why treating troublesome menopausal symptoms appropriately can be part of supporting wider health.

Current NICE guidance says menopause-specific CBT can be considered for sleep problems associated with vasomotor symptoms, either alongside other management options such as HRT or when other options are unsuitable or not preferred.

If menopausal symptoms are significantly disrupting your sleep, it is worth discussing treatment options with your GP or menopause clinician.

Does poor sleep make you gain weight?

Poor sleep does not guarantee weight gain.

But repeated sleep restriction can create conditions that may make energy balance more difficult.

For example:

sleep restriction

may lead to:

greater appetite + more eating opportunities + larger portions

while also contributing to:

fatigue + less movement

That combination can matter over time.

Clinical-trial evidence suggests insufficient sleep may contribute to increased food intake and weight gain, although individual responses vary.

So the answer is not:

“Sleep more and weight will fall off.”

The better message is:

sleep is one of several factors that can make healthy eating and metabolic regulation easier or harder.

What about cravings?

Cravings are often blamed entirely on blood glucose or hormones.

But they can arise for many reasons.

Poor sleep may be one.

Other contributors can include:

• long gaps between meals
• inadequate food intake
• low protein intake
• habit
• stress
• emotional eating
• food restriction
• alcohol
• environment
• menstrual-cycle changes

If cravings are consistently worse after poor sleep, that is useful information.

Rather than immediately removing more foods, we can ask:

what is driving the need for them?

Why eating too little can make matters worse

A woman trying to manage midlife weight gain may respond by eating increasingly less.

If she is also sleeping poorly, she may then be dealing with:

• fatigue
• hunger
• restricted food intake
• greater food preoccupation
• reduced training recovery

That can become difficult to sustain.

Sometimes the more useful strategy is not to restrict harder.

It is to create meals that better support:

• satiety
• muscle
• energy
• blood glucose
• consistency

while also working on the sleep problem itself.

Building meals for a tired day

There is no perfect meal for poor sleep.

But when someone is tired, I like to reduce the amount of decision-making needed.

A simple meal structure might include:

Protein

Examples include:

• eggs
• yoghurt
• fish
• poultry
• tofu
• tempeh
• beans
• lentils

Fibre-rich carbohydrate or plant foods

For example:

• vegetables
• fruit
• pulses
• wholegrains

A source of healthy fat

Such as:

• olive oil
• nuts
• seeds
• avocado

The purpose is not to create a formula that everyone must follow.

It is to make meals more satisfying and less dependent on willpower when energy is low.

Caffeine: useful, but timing matters

Caffeine can temporarily improve alertness when you are tired.

But using increasing amounts of caffeine to compensate for poor sleep can become part of the problem.

Caffeine later in the day may make it harder to sleep that night, potentially creating a cycle:

poor sleep → more caffeine → poorer sleep → more caffeine

The NHS advises reducing potential triggers such as caffeine if they worsen hot flushes or night sweats and recommends regular sleep routines through menopause.

If sleep is difficult, it can be useful to look at:

• total caffeine intake
• timing
• individual sensitivity

rather than assuming morning coffee has to disappear entirely.

Alcohol and sleep

Alcohol may make you feel sleepy initially.

But it can disrupt sleep quality later in the night.

It may also:

• add significant energy
• affect appetite and food choices
• worsen night sweats in some women

The NHS recommends staying within alcohol guidelines and notes that alcohol may affect menopausal symptoms.

For someone struggling with both sleep and body composition, alcohol is therefore worth including in the wider assessment.

Movement helps more than calorie expenditure

Exercise is not simply about “burning off” food.

Regular physical activity can support:

• sleep
• mood
• insulin sensitivity
• cardiovascular health
• muscle
• stress management

If you are exhausted after a poor night, an intense workout may not always be realistic.

But that does not make movement pointless.

Walking, light activity and maintaining everyday movement can still matter.

The aim is consistency, not punishment.

What I look at in practice

When someone tells me that appetite, cravings or weight have changed through midlife, I want to understand what is happening around the eating, not only what is on the plate.

How are you sleeping?

Are you struggling to fall asleep?

Waking frequently?

Waking because of night sweats?

Waking very early?

When did the sleep change?

Did it coincide with perimenopause?

A stressful period?

A medication change?

A change in alcohol use?

What happens the following day?

Are you hungrier?

Do cravings increase?

Does breakfast disappear because you are rushing?

Do you rely on caffeine?

Does exercise become less likely?

What does your diet look like?

Is protein adequate?

Are meals satisfying?

Are you unintentionally under-eating earlier in the day and compensating later?

What else might be contributing?

Depending on the pattern, we may also need to consider:

• thyroid health
• iron status
• glucose regulation
• medication
• mental health
• sleep disorders

Sleep is part of the picture, not automatically the whole explanation.